1. Field of the Invention
This invention relates to a device for controlling ignition timing in an internal combustion engine, more specifically to a device for controlling ignition timing in an internal combustion engine which improves the transient response of the internal combustion engine by detecting acceleration and other such transient conditions of engine driving operation on the basis of the cylinder pressure of the engine and regulating the ignition timing accordingly.
2. Description of the Prior Art
Conventional devices for controlling ignition timing in internal combustion engines have been arranged to determine a primary ignition timing control value with reference to the engine rpm and load state and then to compensate the primary ignition timing control value on the basis of transient conditions of the engine driving operation detected from the degree of throttle valve opening and the like. One example of such a device is disclosed in Japanese Patent Publication No. 58(1983)-40027. There have also recently been proposed devices which carry out ignition timing on the basis of detected cylinder pressure while detecting the transient conditions on the basis of the throttle valve opening in the same conventional manner. As one example of such a device there can be mentioned that disclosed in Japanese Patent Publication No. 56(1981)-21913.
The first mentioned device has a number of important drawbacks. First, it requires a particular detection means for detecting the transient conditions as well as complex circuitry for processing the outputs of the detection means. As a result the device is inconveniently complex in structure. Further, as feedback control is not carried out, little can be expected in terms of compensation effect. With this type of device, therefore, there has been no choice but to set the primary control value with high accuracy and relegate the compensatory function to a minor, secondary role. Because of this, the volume of mapped control values tends to grow very large so that the device is also disadvantageous in that it has to be provided with a large capacity memory.
The second type of device referred to above is similarly disadvantageous in the point of requiring a similar detection means for detecting the transient conditions and a similar complex circuitry for processing the outputs of the detection means. While the device does employ a feedback control system in which the state of combustion of the engine is directly detected, the deviation of the actual maximum cylinder pressure angle from a target maximum-pressure angle, i.e. ATDC 10.degree.-15.degree., is determined and the control value is set so as to reduce and eliminate the deviation, it teaches nothing whatsoever about how the deviation, particularly the deviation at the time the engine is in a transient state, can be eliminated without impairing drivability. The device further provides no countermeasure with respect to knocking, the phenomenon that is highly likely to occur when the engine is in the transient state.